During office processing of the data, checks were performed on records to ensure that specific values lay within valid ranges and relationships between items were within limits deemed acceptable for the purposes of the survey. This was in addition to edits which were triggered in the instrument at the time of the interview. These checks were also designed to detect errors which may have occurred during response entry and processing and to identify cases which although not necessarily errors, were sufficiently unusual or close to agreed limits to warrant examination.

Data available from the surveys are essentially ‘as reported’ by respondents. In some cases it was possible to correct errors or inconsistencies in the data which were originally recorded through reference to other data in the record, including interviewer comments; in other cases this was not possible and some errors and inconsistencies remain on the data file.

The data from the biomedical results received from the pathology lab was linked to the self-reported data by the AHS reference number. Where there were inconsistencies between reference numbers on the biomedical results file and the survey file, these were investigated further to ensure that the results were attached to the correct respondent.